The observed variability of the separation between knots, as discussed in Sect. REF , has usually been interpreted as the result of the superposition of several ejection modes with different periodicity [1]}, related to velocity or density variations in the ejection process. Here, we propose that the minimum time interval between two consecutive knots corresponds to the period of the variable ejection process and that the radial velocity fluctuations reported in Table REF  result from this variability. Then, the apparent bimodal distribution of knot separation can simply be accounted for by dynamical interactions in the nearby environment of protostar A.
